In the related art, a method in which electromagnetic waves are radiated in order to measure a characteristic of a measurement target material is known. An example of such a method is disclosed in the below-cited Patent Document 1. In Patent Document 1, a perforated-structure body is provided in which a large number of apertures are arranged. The perforated-structure body is irradiated with electromagnetic waves from a direction orthogonal to the apertures. Next, a measurement target material is arranged on the perforated-structure body and the perforated-structure body is irradiated with electromagnetic waves. A characteristic of the measurement target material is measured using the difference between the transmittance of the electromagnetic waves in the case where the measurement target material is not arranged on the perforated-structure body and the transmittance of the electromagnetic waves in the case where the measurement target material is arranged on the perforated-structure body. In Patent Document 1, it is described that for example the reflection of electromagnetic waves may be used instead of the transmittance of electromagnetic waves.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-10366